Remove duplication.
diff --git a/Doc/library/collections.rst b/Doc/library/collections.rst
index bf1fe2c..e512bf1 100644
--- a/Doc/library/collections.rst
+++ b/Doc/library/collections.rst
@@ -191,7 +191,7 @@
* The multiset methods are designed only for use cases with positive values.
The inputs may be negative or zero, but only outputs with positive values
are created. There are no type restrictions, but the value type needs to
- support support addition, subtraction, and comparison.
+ support addition, subtraction, and comparison.
* The :meth:`elements` method requires integer counts. It ignores zero and
negative counts.